Bright, stable, and water-soluble CuInS2/ZnS nanocrystals passivated by cetyltrimethylammonium bromide

Abstract

Lee et al., 2015. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.We report a highly bright and stable aqueous dispersion of CuInS2/ZnS (CIS/ZnS) nanocrystals (NCs) using surfactant-assisted microemulsion and cold treatment.CIS/ZnS NCs were facilely synthesized via a stepwise, consecutive hybrid flow reactor approach. To stabilize the optical properties of hydrophobic CIS/ZnS NCs, cetyltrimethylammonium bromide (CTAB) was chosen as a matrix for aqueous phase transfer. As the result, a high quantum yield (QY) of 56.0% and excellent photostability were acquired in aqueous media. For removing excessive surfactants, cold treatment (4°C) of the CTAB-water solution was adopted to prevent further agglomeration of CIS/ZnS NCs, which could secure high stability over 6 months (less 2% reduction in QY). The optical features and structure of the obtained CTAB stabilized CIS/ZnS (CTAB-CIS/ZnS) NCs have been characterized by UV-vis and photoluminescence (PL) spectroscopies, XRD, XPS, EDX, and TEM. The high stability and PL of water soluble CTAB-CIS/ZnS NCs suggest their potential in nanoelectronics and bioapplications.

Synthesis of Hydrophilic CuInS2/ZnS Quantum Dots with Different Polymeric Shells and Study of Their Cytotoxicity and Hemocompatibility

“…To transfer CIS-based QDs to aqueous solutions, we used two common approaches: encapsulation with amphiphilic polymers 24,28,29 or micelles 9,23 and ligand exchange. 12,17 As a rule, the first approach leads to higher PLQY after hydrophilization due to the initial hydrophobic ligands are not removed from the QDs surface. The most frequently used amphiphilic polymer for QDs hydrophilization is PMAO due to its commercially availability and low cost.…”

“…On the basis of results published before, it can be concluded that both CIS structure and ZnS passivating shell significantly influence QDs photostability in organic solutions. 13,15,16 To the best of our knowledge, the photostability in aqueous solutions was studied only in one work, 17 where it was surprisingly shown that hydrophilic CIS/ ZnS QDs covered with CTAB showed better photostability than the initial hydrophobic QDs.…”

Brightly luminescent colloidal Ag–In–S nanoparticles stabilized in aqueous solutions by branched polyethyleneimine

“…[2]. To be appropriate for introduction into the hydrophilic bio-systems such NPs should be precipitated, subjected to the ligand exchange to modify the NP surface with bifunctional ligands like organic mercaptoacids rendering the NPs soluble and stable in water and allowing the NP conjugation to biomolecules [2,5,12,13,16]. These procedures decrease the PL QY inevitably by a factor of 2-3.…”

“…In particular, big expectations are associated with ternary indium-based chalcopyrites [1,19,20], such as CuInS 2 and CuInS 2 /ZnS NPs [13][14][15][16]20], non-stoichiometric Cu-In-S [20,21] and Ag-In-S NPs [10], CuInS x Se 2-x NPs [22], AgInS 2 and AgInS 2 /ZnS NPs [9,11,23,24] that can also be produced by the well-known "hot injection" methods with the PL QY reaching 40-65% [1,14,21,22]. Such compounds combine a series of very attractive features, including relatively low toxicity and ability to preserve chalcopyrite structure in a broad range of NP sizes and non-stoichiometries [1,19,20,24,25].…”